I don't know for sure so am guessing to a large degree but I agree with you that we probably had Pep lined up in 2012. We knew even then that there was going to be big trouble with Mancini, as he'd already sidelined Brian Marwood & made it clear he wouldn't work with the incoming Txiki Begiristain.
According to the Der Spiegel articles, Garry Cook was already quite exasperated with his financial demands and Cook left us in September 2011, so we knew there was trouble brewing. I suspect that him winning the title put us in an awkward position but he'd at least threatened to leave then or, if one reliable report I heard is true, actually handed in his notice.
Whatever, we blinked first and offered him a new contract but this one limited his payout on termination to 2 years. I suspect that left Pep high and dry and he had to take a 12-month sabbatical before joining Bayern.